TranGen Question!

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Muhammad89

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How do we know a Generator Has been loaded? and is it possible to have an efficiency of more than 100%! I have worked out an example that asked to find the efficiency of a transformer and with applying the next equation(Output/Input)*100, it turned to be 112%. can this be possible in reality?


Muhammad89
 
No. The transformer has only one input of energy -- the primary; output power divided by input power is efficiency and you can never get more out than you put in. In fact, a transformer, although a pretty efficient device, isn't perfect, and there will be losses in the core from eddy currents and poor coupling and resistive losses in both the primary and secondary.

Think about this: a transformer that is 90% efficient running at full load will get warm to the touch. If a transformer was 120% efficient, then would it actually get cool to the touch?

Dean
 
Resistive losses are normally the dominating factor.

It's possible that you measured the transformer voltage with no load and assumed it stayed the same when you connected the load or make a mistake in your calculations.

My guess is that you've got the efficiency calcultaion wrong, you probably did [latex]\frac{\text{Power in}}{\text{Power out}}[/latex] instead of [latex]\frac{\text{Power out}}{\text{Power in}}[/latex].
 
Muhammad89 said:
Can this be possible in reality?
Click to expand...

For example, based on the nameplate data the small transformer that charges my cell phone is 65% efficient, and larger transformers are more efficient (Economy of Scale)
**broken link removed**
perhaps up to 99%.

You need to measure RMS values and possibly take Power Factor into account.
 
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Dean Huster said:
a transformer that is 90% efficient running at full load will get warm to the touch. If a transformer was 120% efficient, then would it actually get cool to the touch?

Dean
Click to expand...

Hah thats actually quite a good question! I'd think it would just stay room temp, but its still a good question lol
 
Muhammad89 said:
... it turned to be 112%. can this be possible in reality?


Muhammad89
Click to expand...

No, not a chance. Double check your measurements and calculations. If you still get >100% efficiency, check them again. You can't have a unity of greater than 1. Now you have people out there claiming to have built/developed over-unity generators that can produce more power that it consumes. And of course, they will fudge the numbers to get their calculations to come out right. It's a bunch of hog wash.
 
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that was fairly convincing about the Eff of the trans, however, I see no answers on my 1st question, how do we recognize a Gen has been loaded?
 
Muhammad89 said:
how do we recognize a Gen has been loaded?
Click to expand...

It's speed drops because it requires more torque input to the drive shaft. Therefore one has to drive it with more mechanical power from the prime mover(e.g. more fuel, more steam..etc you name it) to return its speed to that before the application of the load.
 
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